Clean rooms are used in many industries, such as food processing plants, electrical manufacturing and chemical manufacturing, where the processing is sensitive to contamination. Frequent wash-downs of clean rooms can include use of harsh soaps and disinfectant chemicals that are sprayed and scrubbed on the room surfaces.
Cracks, crevasses, cavities and other openings in a clean room are undesirable because they can collect and shelter contaminants and foster bacterial growth so as to compromise the cleanliness of the environment. One source of such a home for retaining contaminants and bacterial breading is electrical device boxes of the type that carry switches, outlets and the like. These boxes are typically of a multi-piece construction with various cracks and openings. They have seams that can collect foreign matter and are hard to clean.
Another issue is that the electrical boxes are subject to the hostile environment of the clean room, including being exposed to harsh and abrasive cleaning chemicals. Conventional water-tight boxes constructed of cast aluminum, plastic or malleable cast iron are undesirable because cast aluminum is prone to a high degree of corrosion from wash-down chemicals, plastic boxes are structurally inferior, and cast iron boxes are also subject to corrosion and can have a roughened surface that promotes bacterial growth.
It is disclosed in U.S. Pat. No. 5,693,909 to use stainless steel for an electrical box to withstand the rigors of the wash-down with the harsh chemicals. The disclosed box has no seams to collect dirt and foster growth of bacteria. The entirety of U.S. Pat. No. 5,693,909 is hereby incorporated by reference and made part of this application.
The box of U.S. Pat. No. 5,693,909 can be made as a single junction box or as a double junction box. In use, the opening of the box into the room must be covered with a cover plate. Thus, there must be provided both single and double face plates corresponding to the single junction box or as a double junction box that is employed. A single face plate cannot be attached to the double junction box disclosed in U.S. Pat. No. 5,693,909. Therefore, there is a need to provide for an improved electrical junction box for clean room environments.